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Linker histone H1 represses recombination at the ribosomal DNA locus in the budding yeast Saccharomyces cerevisiae
Author(s) -
Li Chonghua,
Mueller John E.,
Elfline Megan,
Bryk Mary
Publication year - 2008
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2007.06101.x
Subject(s) - biology , chromatin , genetics , histone h1 , saccharomyces cerevisiae , histone methylation , histone , histone h2a , microbiology and biotechnology , gene , dna methylation , gene expression
Summary Several epigenetic phenomena occur at ribosomal DNA loci in eukaryotic cells, including the silencing of Pol I and Pol II transcribed genes, silencing of replication origins and repression of recombination. In Saccharomyces cerevisiae , studies focusing on the silencing of Pol II transcription and genetic recombination at the ribosomal DNA locus (rDNA) have provided insight into the mechanisms through which chromatin and chromatin‐associated factors regulate gene expression and chromosome stability. The core histones, H2A, H2B, H3 and H4, the fundamental building blocks of chromatin, have been shown to regulate silent chromatin at the rDNA; however, the function of the linker histone H1 has not been well characterized. Here, we show that S. cerevisiae histone H1 represses recombination at the rDNA without affecting Pol II gene silencing. The most highly studied repressor of recombination at the rDNA is the S ilent i nformation r egulator protein Sir2. We find that cells lacking histone H1 do not exhibit a premature‐ageing phenotype nor do they accumulate the rDNA recombination intermediates and products that are found in cells lacking Sir2. These results suggest that histone H1 represses recombination at the rDNA by a mechanism that is independent of the recombination pathways regulated by Sir2.